1. Field of the Invention
This invention relates to methods and devices used for electrically connecting medical glucose monitors to glucose sensor electrodes as well as for testing the operation of the glucose monitors, monitor cables and glucose sensors.
2. Description of the Related Art
Over the years, a variety of implantable electrochemical sensors have been developed for detecting or quantifying specific agents or compositions in a patient's blood. For instance, glucose sensors are being developed for use in obtaining an indication of blood glucose levels in a diabetic patient. Such readings are useful in monitoring or adjusting a treatment regimen which typically includes the regular administration of insulin to the patient. Thus, blood glucose readings can improve medical therapies with semi-automated medication infusion pumps of the external type, as generally described in U.S. Pat. Nos. 4,562,751; 4,678,408; and 4,685,903; or automated implantable medication infusion pumps, as generally described in U.S. Pat. No. 4,573,994, which are incorporated herein by reference.
Generally, small and flexible electrochemical sensors can be used to obtain periodic readings over an extended period of time. In one form, flexible subcutaneous sensors are constructed in accordance with thin film mask techniques in which an elongated sensor includes thin film conductive elements encased between flexible insulative layers of polyimide sheets or similar material. Such thin film sensors typically include a plurality of exposed electrodes at one end for subcutaneous placement with a user's interstitial fluid, blood, or the like, and a corresponding exposed plurality of conductive contacts at another end for convenient external electrical connection with a suitable monitoring device through a wire or cable. Typical thin film sensors are described in commonly assigned U.S. Pat. Nos. 5,390,671; 5,391,250; 5,482,473; and 5,586,553 which are incorporated herein by reference.
Thin film sensors generate very small electrical signals which can be read by external glucose monitors. These monitors can be portable, and can be attached to the patient, such as for example, on a belt clip. Applicant's clinical studies have shown that an electrical cable may be provided for the transmission of these small signals from the sensors to the glucose monitor. But given the environment in which these cables are used, special characteristics can be useful.
Thus a glucose monitoring system includes connectors between the cables, leads, electrodes and monitors such as those described in pending U.S. patent application Ser. No. 09/346,835, filed Jul. 2, 1999 and entitled “Insertion Set for a Transcutaneous Sensor” and U.S. patent application Ser. No. 09/377,472, filed Aug. 19, 1999 and entitled “Telemetered Characteristic Monitor System and Method of Using Same, both of which are incorporated herein by reference. Although a well designed system will have minimal operational problems, it is possible that a problem might arise with the integrity of the cables, sensor electrodes or monitor during their use. The system connectors or the cables may become loose or bent, resulting in a poor or open circuit. The sensor electrodes could degrade. The glucose monitor could become inoperative due to any number of causes. Thus, it is desirable to provide a system that is simple to use so that a patient can easily identify any operational problems with the system.